The present disclosure relates to subject matter contained in priority Japanese Patent Application No. 2002-3142, filed on Jan. 10, 2002, the contents of which is herein expressly incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a method for inspecting relay contacts for a contact weld in a battery power source device that is installed in large-sized hybrid vehicles.
2. Description of Related Art
A battery power source device employed as a power source for a motor to drive vehicles such as hybrid cars includes a battery pack block, having a plurality of battery modules (e.g., 30 battery modules) connected in series, each battery module having a plurality of rechargeable batteries (e.g., 6 batteries) connected in series. To provide control to the operating condition of the battery pack block, the battery power source device further includes a battery ECU (Electronic Control Unit) for detecting the voltage, current, and temperature of the battery pack block to detect abnormal condition thereof or provide various types of control thereto in accordance with the results of the detection. Such a battery power source device is configured to supply power to the driving motor and to be charged by the power from the generator of the vehicle.
To supply a large power to large vehicles, battery pack systems, each having a battery pack block and an ECU in combination, are designed to connect with each other serially and/or in parallel.
With this arrangement, there is a possibility of a contact weld occurring at an open/close contact for opening or closing an input/output circuit in the battery pack block. A contact weld would make it difficult not only to prevent operators from receiving an electric shock during assembly or maintenance but also to provide proper control under abnormal conditions. What is worse, a contact weld in an open/close contact would ruin the function for limiting an inrush current, thereby causing an excessive inrush current to exert a harmful effect.
A small hybrid vehicle as requiring a relatively small power has usually one battery pack block. In this case, as shown in FIG. 4, a battery pack block 22 is checked for a contact weld of its open/close contacts by connecting a voltage sensor 17 between a positive charge/discharge terminal 15 and a negative charge/discharge terminal 16 of a battery power source device 21 to check open/close contacts 24, 25, and 26 for a contact weld.
First, the secondary open/close contact 26 on the positive side is turned on, and a resistor 27 is allowed to limit an inrush current charged into a smoothing capacitor 18 that is connected between the positive charge/discharge terminal 15 and the negative charge/discharge terminal 16. At this time, when the voltage sensor 17 detects no voltage nearly equal to the voltage of the battery pack block 22, the open/close contact 25 on the negative side is determined not to be welded, whereas being determined to be welded when an approximately equal voltage has been detected. In other words, the contact is determined to remain closed due to a contact weld. Suppose that the open/close contact 24 and the secondary open/close contact 26 on the positive side are turned off and the open/close contact 25 on the negative side is then turned on, and that the voltage detected by the voltage sensor 17 is sufficiently lower than the voltage of the battery pack block. In this case, the open/close contact 24 and the secondary open/close contact 26 on the positive side are determined not to be welded, whereas either the open/close contact 24 or the secondary open/close contact 26 is determined to be welded when a voltage nearly equal to the voltage of the battery pack block 22 is detected.
However, according to the conventional method described above, the battery power source device 21 had to be externally provided with the voltage sensor 17 and connected to the voltage sensor 17 via wiring. Additionally, a method for inspecting a battery power source device employing a plurality of battery pack blocks by means of the voltage sensor 17 for a contact weld would require a long time for the contact weld inspection.
An object of the present invention is to provide a method for inspecting relay open/close contacts for a contact weld in a battery power source device, the method enabling the inspection of the open/close contacts for a contact weld to be carried out by the relays that are provided in each of a plurality of battery pack systems of the battery power source device.
To achieve the aforementioned object, the present invention provides a method for inspecting relay contacts for a contact weld in a battery power source device. The battery power source device includes: a plurality of battery pack blocks connected serially and/or in parallel, the battery pack blocks each having a plurality of rechargeable batteries serially connected, for charging and discharging operations in a vehicle via a positive charge/discharge terminal and a negative charge/discharge terminal; a plurality of battery ECUs each connected with the battery pack blocks, for controlling operating conditions of the battery pack blocks; and a plurality of charge/discharge circuits each provided to the battery pack blocks, each charge/discharge circuit being provided with a relay open/close contact. A smoothing capacitor is connected between the positive charge/discharge terminal and the negative charge/discharge terminal in the vehicle. According to the method for inspecting relay contacts for a contact weld, the plurality of battery pack blocks allow the battery ECUs one by one in an arbitrary order to close the open/close contacts and deliver an inspection signal to the charge/discharge circuit, and the battery ECU of the other battery pack blocks determines whether the inspection signal has been received via a parallel connection circuit and the smoothing capacitor, thereby determining whether an open/close contact weld of the battery pack blocks has occurred or not. By following the aforementioned procedure on the plurality of battery pack blocks one by one, the open/close contact of a battery pack block that is found to have received the inspection signal is determined to be welded. That is, the welded and thereby closed open/close contact has formed a transmission path through which the inspection signal is transmitted to the battery ECU. By following this procedure successively on each of the battery pack blocks, it is possible to check the open/close contacts provided in all the battery pack blocks for a contact weld.
In the aforementioned method, it is preferable that one of the plurality of battery ECUs is set to a master and the others to slaves, each battery ECU being provided with a communication device and connected to each other via the communication line, and the slave battery ECUs transmit an inspection result of the open/close contacts to the master battery ECU by the communication device via the communication line. The master battery ECU collects the results of inspection of each relay contact for a contact weld and inform of the results an apparatus that uses the battery power source device.
Furthermore, the communication line can be connected to the vehicle, which employs the battery power source device as its drive power source, to form a network and transmit an inspection result to the vehicle therethrough. This makes it possible for the vehicle to know a welded relay contact and provide control to take countermeasures against it.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.